X+y-2z=-3 3x+5y+z=5 4x-7y-2=0

1.x+y+z=-3+2
x+y+z= -1

2.x+y=5-3-5
x+y=-3

3.x-y=0-4+7+2
x-y=5

semoga membantu ..
maaf kalo salah